package org.apache.maven.cli.transfer;

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *  http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */

import java.io.PrintStream;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;

import org.eclipse.aether.transfer.TransferCancelledException;
import org.eclipse.aether.transfer.TransferEvent;
import org.eclipse.aether.transfer.TransferResource;

/**
 * Console download progress meter.
 * 
 * @author <a href="mailto:brett@apache.org">Brett Porter</a>
 */
public class ConsoleMavenTransferListener extends AbstractMavenTransferListener {

  private Map<TransferResource, Long> downloads = new ConcurrentHashMap<TransferResource, Long>();

  private int lastLength;

  public ConsoleMavenTransferListener(PrintStream out) {
    super(out);
  }

  @Override
  public void transferProgressed(TransferEvent event) throws TransferCancelledException {
    TransferResource resource = event.getResource();
    downloads.put(resource, event.getTransferredBytes());

    StringBuilder buffer = new StringBuilder(64);

    for (Map.Entry<TransferResource, Long> entry : downloads.entrySet()) {
      long total = entry.getKey().getContentLength();
      Long complete = entry.getValue();
      // NOTE: This null check guards against
      // http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=6312056
      if (complete != null) {
        buffer.append(getStatus(complete.longValue(), total)).append("  ");
      }
    }

    int pad = lastLength - buffer.length();
    lastLength = buffer.length();
    pad(buffer, pad);
    buffer.append('\r');

    out.print(buffer.toString());
  }

  private String getStatus(long complete, long total) {
    if (total >= 1024) {
      return toKB(complete) + "/" + toKB(total) + " KB ";
    } else if (total >= 0) {
      return complete + "/" + total + " B ";
    } else if (complete >= 1024) {
      return toKB(complete) + " KB ";
    } else {
      return complete + " B ";
    }
  }

  private void pad(StringBuilder buffer, int spaces) {
    String block = "                                        ";
    while (spaces > 0) {
      int n = Math.min(spaces, block.length());
      buffer.append(block, 0, n);
      spaces -= n;
    }
  }

  @Override
  public void transferSucceeded(TransferEvent event) {
    transferCompleted(event);

    super.transferSucceeded(event);
  }

  @Override
  public void transferFailed(TransferEvent event) {
    transferCompleted(event);

    super.transferFailed(event);
  }

  private void transferCompleted(TransferEvent event) {
    downloads.remove(event.getResource());

    StringBuilder buffer = new StringBuilder(64);
    pad(buffer, lastLength);
    buffer.append('\r');
    out.print(buffer.toString());
  }

}
